1. Field of the Invention
The present invention relates generally to angle detectors and more particularly to an angle detector incorporating a self-balancing bridge.
2. Description of the Prior Art
Wind tunnel testing requires a small detector that can be mounted inside a test airplane model to measure angle of attack or the rotation of the model about a horizontal axis. A device of this type has been described in the paper "Capacitance Pickup Measures Small Forces," J. Dimeff and T. B. Fryer, Electronics, Vol. 30, No. 2, Feb. 1957, pp. 143-145. The detector utilizes a potentiometer-type transducer with a stationary, capacitance-type wiper. A remote potentiometer is connected in parallel with the transducer to form a bridge circuit. When the model is moved, the transducer is moved and an a-c error signal is generated at the capacitance-type wiper. The error signal is amplified and used to drive a servo motor which is coupled to the wiper of the remote potentiometer by means of a gear train. The wiper is slewed in such a direction as to balance the bridge circuit. The angle readout is in two forms: (1) a front panel indication from a mechanical counter driven by the servo-motor gear train; and (2) the analog output of an isolated potentiometer driven by the servo-motor gear train.